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A heartier appetite is linked to more rapid infant growth and to genetic predisposition to obesity, according to two papers published in JAMA Pediatrics today.

The studies investigated how weight
gain is linked to two key aspects of appetite, namely lower satiety responsiveness
(a reduced urge to eat in response to internal ‘fullness’ signals) and higher
food responsiveness (an increased urge to eat in response to the sight or smell
of nice food).

The first paper reveals that
infants with a heartier appetite grew more rapidly up to age 15 months,
potentially putting them at increased risk for obesity.

The authors used data from non-identical,
same-sex twins born in the UK in 2007. Twin pairs were selected that differed
in measures of satiety responsiveness (SR) and food responsiveness (FR) at 3
months, and their growth up to age 15 months was compared. Within pairs, the
infant who was more food responsive or less satiety responsive grew faster than
their co-twin.

The more food responsive twin was
654g heavier (1.4lbs) than their co-twin at six months and 991g heavier (2.1lbs)
at 15 months. The less satiety responsive twin was 637g heavier (1.4lbs) than
their co-twin at six months and 918g heavier (2lbs) at 15 months.

“Obesity is a major issue in
child health” says Professor Jane Wardle, lead author of the study from the UCL
Health Behaviour Research Centre. “Identifying factors that promote or protect
against weight gain could help identify targets for obesity intervention and
prevention in future. These findings are
extremely powerful because we were comparing children of the same age and same
sex growing up in the same family in order to reveal the role that appetite
plays in infant growth.

Children with lower satiety sensitivity could be taught techniques that might improve their fullness signals when eating, such as slowing their eating speed. Another approach might be to provide better advice to parents and children about appropriate portion sizes, limiting access to ‘second helpings’ and ensuring tempting treats are out of sight between meals.

Dr Clare Llewellyn (UCL Health Behaviour Research Centre)

“It might make life
easy to have a baby with a hearty appetite, but as she grows up, parents may
need to be alert for tendencies to be somewhat over-responsive to food cues in
the environment, or somewhat unresponsive to fullness. This behaviour
could put her at risk of gaining weight faster than is good for her.”

The second JAMA Pediatrics paper, in collaboration with King’s College London,
sheds further light on the way that appetite, particularly low satiety
responsiveness, acts as one of the mechanisms underlying genetic predisposition
to obesity.

The researchers accessed data
from 2,258 10-year-old children born in the UK between 1994 and 1996. The team created a polygenic obesity risk score
(PRS) for each child to estimate their genetic susceptibility to obesity, by
adding up the number of higher-risk alleles from 28 obesity-related genes. Higher PRS scores indicated a higher genetic
predisposition to obesity.

The PRS scores were then examined
to determine the correlation with the children’s satiety responsiveness and adiposity
(body fatness).

“As expected, we found that
children with a higher PRS score (more ‘obesity-risk’ genetic variants) were
likely to have larger BMI and waist circumference,” says Dr Clare Llewellyn,
lead author from the UCL Health Behaviour Research Centre. “But more
importantly, we also found that these children were more likely to have low
satiety responsiveness.

“This suggests that satiety responsiveness
could be targeted for pharmacological and behavioural interventions, to prevent
or treat obesity. For example, children with lower satiety sensitivity could be
taught techniques that might improve their fullness signals when eating, such
as slowing their eating speed. Another approach might be to provide better
advice to parents and children about appropriate portion sizes, limiting access
to ‘second helpings’ and ensuring tempting treats are out of sight between
meals.”